Heat oven to 350 degrees F. Coat 2 baking sheets with nonstick cooking spray. Whisk flour, baking powder, baking soda and salt together; set aside.
Beat butter and granulated sugar together until blended. Add egg, ricotta and vanilla, beating until combined.
On low speed, add flour mixture and beat until blended. Drop by tablespoonfuls onto prepared pans. Bake at 350 degrees F for 14 minutes or until lightly browned around edges. Let cool on sheets 3 minutes, then remove to rack to cool completely.
Beat confectioners sugar and milk together until well blended. Dip tops of cookies into glaze and set aside until glaze has hardened.